As a conventional four-way, there is the one in which at least a sliding surface with respect to a valve seat of a slide valve in a switching valve is made of self-lubricating resin, and the remaining portion except for the mentioned sliding surface of the mentioned slide valve is made of thermosetting resin or crystalline thermoplastic resin having no ester group or amino group (for example, refer to Patent Document 1).
Further, there is another one in which a body of a three-way switching valve switching a port B so as to communicate to a port A, into which a refrigerant of high temperature and high pressure is guided, or to a port D from which a refrigerant of low temperature and low pressure is guided out, and a body of a three-way switching valve switching a port C so as to communicate to a port A or a port D, are separated. Common ports A and D are connected to each other through pipes. A passage of each body in which a refrigerant flows is surrounded by a heat-insulating sleeve and a heat-insulating plug. And a plug forming a valve element is made of a material of low thermal conductivity (for example, refer to Patent Document 2).    (Patent Document 1) Japanese Patent Publication (unexamined) No. 201297/1999 (page 1, FIG. 2)    (Patent Document 21 Japanese Patent Publication (unexamined) No. 254453/2003 (page 1, FIG. 1)